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Moved separate functions in halton sampler inline into the match.

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Doesn't really have much impact, but makes me feel better for some
reason.
This commit is contained in:
Nathan Vegdahl 2019-07-07 17:39:34 +09:00
parent 103775f0e9
commit 70721be8e0
1 changed files with 39 additions and 48 deletions
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73
sub_crates/halton/build.rs
View File

@ -98,59 +98,35 @@ pub const MAX_DIMENSION: u32 = {};
f.write_all(
format!(
r#"
#[inline]
pub fn sample(dimension: u32, index: u32) -> f32 {{
let mut index = index;
match dimension {{"#
)
.as_bytes(),
)
.unwrap();
for i in 0..NUM_DIMENSIONS {
f.write_all(
format!(
r#"
{} => halton{}(index),"#,
i, primes[i]
)
.as_bytes(),
)
.unwrap();
}
f.write_all(
format!(
r#"
_ => panic!("Exceeded max dimensions."),
}}
}}
"#
)
.as_bytes(),
)
.unwrap();
// Write the special-cased first dimension
f.write_all(
format!(
r#"
// Special case: radical inverse in base 2, with direct bit reversal.
fn halton2(mut index: u32) -> f32 {{
// Special case: radical inverse in base 2, with direct bit reversal.
0 => {{
index = (index << 16) | (index >> 16);
index = ((index & 0x00ff00ff) << 8) | ((index & 0xff00ff00) >> 8);
index = ((index & 0x0f0f0f0f) << 4) | ((index & 0xf0f0f0f0) >> 4);
index = ((index & 0x33333333) << 2) | ((index & 0xcccccccc) >> 2);
index = ((index & 0x55555555) << 1) | ((index & 0xaaaaaaaa) >> 1);
return (index as f32) * (1.0 / ((1u64 << 32) as f32));
}}
"#
}}"#,
)
.as_bytes(),
)
.unwrap();
// The rest of the dimensions.
for i in 1..NUM_DIMENSIONS {
// Skip base 2.
let base = primes[i];
// Based on the permutation table size, we process multiple digits at once.
@ -187,26 +163,28 @@ fn halton2(mut index: u32) -> f32 {{
f.write_all(
format!(
r#"
fn halton{}(index: u32) -> f32 {{
{} => {{
static PERM{}: [u16; {}] = [{}];"#,
base,
i,
base,
perm.len(),
perm_string
)
.as_bytes(),
)
.unwrap();;
.unwrap();
f.write_all(
format!(
r#"
return (unsafe{{*PERM{}.get_unchecked((index % {}) as usize)}} as u32 * {} +"#,
return unsafe {{(
*PERM{}.get_unchecked((index % {}) as usize) as u32 * {}"#,
base, pow_base, power
)
.as_bytes(),
)
.unwrap();;
.unwrap();
// Advance to next set of digits.
let mut div = 1;
@ -216,20 +194,21 @@ fn halton{}(index: u32) -> f32 {{
f.write_all(
format!(
r#"
unsafe{{*PERM{}.get_unchecked(((index / {}) % {}) as usize)}} as u32 * {} +"#,
+ *PERM{}.get_unchecked(((index / {}) % {}) as usize) as u32 * {}"#,
base, div, pow_base, power
)
.as_bytes(),
)
.unwrap();;
.unwrap();
}
f.write_all(
format!(
r#"
unsafe{{*PERM{}.get_unchecked(((index / {}) % {}) as usize)}} as u32) as f32 *
(0.999999940395355224609375f32 / ({}u32 as f32)); // Results in [0,1).
}}
+ *PERM{}.get_unchecked(((index / {}) % {}) as usize) as u32
)}} as f32
* (0.999999940395355224609375f32 / ({}u32 as f32)); // Results in [0,1).
}}
"#,
base,
div * pow_base,
@ -238,8 +217,20 @@ fn halton{}(index: u32) -> f32 {{
)
.as_bytes(),
)
.unwrap();;
.unwrap();
}
f.write_all(
format!(
r#"
_ => panic!("Halton sampling: exceeded max dimensions."),
}}
}}
"#
)
.as_bytes(),
)
.unwrap();
}
/// Check primality. Not optimized, since it's not performance-critical.